In 1988 when they did the C-14 testing, AMS was a relatively new C-14 technique and had only been in use for a few years.
“In 1982, AMS labs began processing archaeological samples for radiocarbon dating.”
https://en.wikipedia.org/wiki/Accelerat … ectrometry
It would be unwise to rely solely on a new technique and would’ve made more sense to also use the conventional method (decay counting) of C-14 dating.
Measurements are traditionally made by counting the radioactive decay of individual carbon atoms by gas proportional counting or by liquid scintillation counting. For samples of sufficient size (several g carbon) this method is still widely used in the 2000s. Among others, all the tree ring samples used for the calibration curves, were determined by these counting techniques. Such decay counting, however, is relatively insensitive and subject to large statistical uncertainties for small samples. When there is little carbon-14 to begin with, the long radiocarbon half-life means that very few of the carbon-14 atoms will decay during the time allotted for their detection, resulting in few disintegrations per minute.
Though AMS is more sensitive than decay counting, by using the traditional method also, it would’ve been evidence to validate the results of AMS.
This was originally the plan; they would use both decay counting and AMS to date the shroud. Four labs would use the traditional method and three labs would use the new method.
– the test would be performed concurrently by seven laboratories, under the joint supervision of the Pontifical Academy of Science, the archbishop of Turin, and the British Museum;
– both dating methods would be adopted
However, the church changed the procedure and said only AMS can be used and this meant only 3 labs can do the test.
The Vatican subsequently decided to adopt a different protocol instead.
– On April 27, 1987, a Vatican spokesperson announced to the newspaper La Stampa that the procedure would likely be performed by two or three laboratories at most;
– On October 10, Cardinal Anastasio Ballestrero officially announced to the seven laboratories that the proportional counter method would not be used because this method would require too much Shroud material (gram quantities rather than milligram quantities). Only three laboratories, namely Oxford, Tucson, and Zürich, would be provided with Shroud samples to be tested.
The labs heavily criticized this change as reported in New Scientist (Jan 1988):
“If one of the laboratories pulls out, then the test will be virtually meaningless.”
“As you are aware, there are many critics in the world who will scrutinize these measurements in great detail. The abandonment of the original protocol, and the decision to proceed with only three laboratories will certainly enhance the scepticism of these critics.”
Harry Gove (who was one of the defacto leaders of the C-14 labs and also from one of the labs that got booted) stated, “I hope the three laboratories stand firm and say to hell with you, let’s get a result we all believe in, or leave it undated.”
So, by the labs own testimony, the C-14 results are virtually meaningless, the scepticism has been enhanced, and it has a result we all don’t believe in.